Siemens PLC S7 300/400 master relays orders

Main control relay (Master Control Relay), abbreviated as MCR. MCR Master relay command is used to control whether normal execution of the instruction in the region, equivalent to a connect and disconnect the flow of the main switch. MCR instruction is not much used, S7-200 is no MCR instruction.

MCRA to activate the master relay instructions, MCRD to deactivate the master relays orders.

Open the master relays orders MCR< in the MCR before you save the results of logical operations on the stack RLO (MCR), close the master relays orders MCR> MCR saved out of the stack in the RLO. MCR< and MCR> used to indicate controlled temporary power cord formation and termination.

MCR instructions can be nested, MCR the MCR can be another zone. MCR stack is a LIFO stack, allowing the maximum nesting depth of 8 levels.

MCRI0.2 control, I0.2 and MCR MCR in the stack level of the same State. MCR bit is 1 when will perform Q4.0 coil MCR control area and MOVE instructions. MCR bit is 0 when Q4.0 is 0.